The present invention relates to handle assembly especially suited for vehicle doors and on tailgates on sport utility vehicles, vans, mini-vans, station wagons, and the like, and, more particularly, to a rear tailgate handle with improved centering and alignment with a mounting base.
Handles that are used to unlatch the tailgate of a vehicle are quite often also used to unlatch a window unit housed in the tailgate. Typically, the handle grip of the assembly assumes a neutral position in which both the window unit and the tailgate are latched. The handle must be rotated from its neutral position to one of two positions, with one position unlatching the tailgate and the other position unlatching the window unit in the tailgate. The direction of the handle grip's rotation dictates which of the two is unlocked for opening. For example, a counterclockwise rotation could unlock the tailgate while a clockwise rotation of the handle would then unlock the window unit in the tailgate. The un-rotated center position of the handle grip defines the neutral position of the assembly in which both the tailgate and the tailgate window are latched.
Conventional tailgate handles include spirally wrapped springs to center a handle grip on the handle mounting base in its neutral position. The spirally wrapped spring has distal ends which engage both the handle mounting base and the handle grip, with the spring being coiled around the handle mounting base to bias the handle grip to the center position, wherein the handle grip is aligned with the handle mounting base.
Several problems have developed with the conventional handles, however. As best shown in FIG. 1 of the drawings, over time the spirally wrapped spring can relax or its distal ends can bend and, eventually, no longer fully bias the handle grip to the center position. This results in a handle grip that is no longer aligned with the handle mounting base by an angular amount X (FIG. 1). Moreover, wrapped spring suppliers do not generally guarantee their springs for a tolerance less than .+-.7 degrees of play. While this particular non-aligned condition does not seriously affect the latching/unlatching function of the handle, the handle does have the appearance of being broken and is not aesthetically pleasing.
Second, the installation of a spirally wrapped spring is labor intensive and difficult. Conventionally, during installation, a first end of the spring is inserted through a slotted opening provided in a collar of the mounting base and into a receiving structure provided in the shaft, with the first end of the spring abutting a first side of the slotted opening to fix the end of the spring in a unilateral direction. The spring is coiled around the collar of the mounting base, and, then, the second end of the spring is inserted through the same opening in the mounting base, abutting a second side of the opening, and into the same receiving structure on the shaft. During such installation, the spring is easily bent; therefore, the quality of the installation and handle performance can be jeopardized. In addition, the spring is hard to grasp during such coiling and requires a significant level of manual dexterity to complete the assembly. During operation, when the handle grip is rotated, the shaft, which is fixed to the handle grip, rotates, pulling the first end of the spring while the second end of the spring is seated against the second side of the slotted opening. This causes the spring to twist and compress until the first end of the spring is rotated from the first side to the second side of the slotted opening, so that both ends of the spring abut the same side of the slotted opening. At this point the spring cannot undergo further twisting or compression, and the handle grip is fully turned in one direction. When the handle is released, the spring will expand and induce rotation in the shaft until the first end of the spring is again abutting the first side of the slotted opening. Similarly, when the handle is rotated in the opposite direction, the same operation occurs except that the second end of the spring will travel from the second side of the slotted opening to the first side of the slotted opening. When operated in this way, the wrapped spring tends to lose tension over time. Coupled with the imprecise tolerance levels in the manufacture of such springs, the loss in tension prevents full return of the shaft and handle grip, resulting in the above non-centered position.
Lastly, a spirally wrapped spring has a relatively low cycle life. The wrapped spring is typically mounted to the mounting base and the shaft of the handle grip at its free ends, but the free ends are bent inward to grip the sides of the slotted opening in the mounting base and the receiving structure in the shaft. The bends at the free ends increase stress concentration factors on the spring and, ultimately, may lead to breakage. When combined with the necessary cycles associated with a tailgate handle over the life span of a vehicle and environmental factors, such as exposure to extreme temperatures and corrosive substances, the overall cycle life of the spring is significantly reduced and, often, reduced to unacceptable levels for automobile manufacturers.
Consequently, there is a need for a door/tailgate handle that can maintain the alignment of the handle grip with its mounting base, perform all required latching/unlatching functions, and yet have a significantly longer cycle life.